Hindawi Publishing Corporation Advances in Materials Science and Engineering Volume 2013, Article ID 501621, 9 pages http://dx.doi.org/10.1155/2013/501621 Research Article White-Ceramic Conversion on Ti-29Nb-13Ta-4.6Zr Surface for Dental Applications Akiko Obata, 1 Eri Miura-Fujiwara, 2 Akimitsu Shimizu, 1 Hirotaka Maeda, 3 Masaaki Nakai, 4 Yoshimi Watanabe, 1 Mitsuo Niinomi, 4 and Toshihiro Kasuga 1 1 Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan 2 Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280, Japan 3 Center for Fostering Young and Innovative Researchers, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan 4 Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan Correspondence should be addressed to Akiko Obata; obata.akiko@nitech.ac.jp Received 16 May 2013; Accepted 12 July 2013 Academic Editor: Delia Brauer Copyright © 2013 Akiko Obata et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy has excellent mechanical properties and bone conductivity. For dental application, TNTZ surfaces were converted to white oxidized layer by a simple heat treatment in air to achieve the formation of aesthetic surfaces. he oxidized layer formed by the heat treatment at 1000 ∘ C for 0.5 or 1 hr was whiter and joined to TNTZ substrate more strongly than that formed by the treatment at 900 ∘ C. he layer consisted of TiO 2 (rutile), TiNb 2 O 7 , and TiTa 2 O 7 and possessed ∼30 m in thickness for the sample heat-treated at 1000 ∘ C and ∼10 m for that heat-treated at 900 ∘ C. he surface average roughness and the wettability increased ater the heat treatment. he spreading and proliferation level of mouse osteoblast-like cell (MC3T3-E1 cell) on the heat-treated sample were almost the same as those on as-prepared one. he cell spreading on TNTZ was better than those on pure titanium (CP Ti) regardless of the heat treatment for the samples. here was no deterioration in the in vitro cell compatibility of TNTZ ater the oxidized layer coating by the heat treatment. 1. Introduction Titanium (Ti) and its alloys have been developed for the use in orthopedic and dental ields, such as joints, plates, screws, and tooth roots. Ti materials show better corrosion resistance than stainless steel and Co-Cr alloys, which are used for biomedical applications, due to the stable titanium oxide ilms formed on their surfaces. Ti alloys are categorized as -type, +-type, and -type, according to the quantities and types of their alloying elements. Various types of Ti alloys have been developed, particularly +-type and -type alloys, which have nontoxic and nonallergic elements, and are expected to be useful for biomedical application [1–4]. Ti- 6Al-4V ELI alloy has been registered in ASTM standardiza- tions and used as bone ixation plates and the stems of artii- cial hip joints. he ELI alloy shows signiicant toughness: an extremely high 0.2% ofset yield strength of 895 MPa, which is higher than those of stainless steel and Co-Cr-Mo alloys [3]. Ti-29Nb-13Ta-4.6Zr (TNTZ) was developed as a low rigidity -type alloy composed of non-toxic and non-allergic elements [1, 2]. he mechanical properties such as tensile properties and fatigue strength of TNTZ are equal to or greater than those of Ti-6Al-4V ELI alloy. Young’s modulus of TNTZ is much lower than that of the ELI alloy, which makes it the preferred material for use in bone ixators. he bone conduction ability of TNTZ is better than that of stainless steel or the Ti-6Al-4V alloy [1]. Diferences in mechanical properties between implant materials and natural bone lead to negative efects, such as stress shielding [2]. he properties of TNTZ have been found to be close to those of bone and expected in medical and dental ields. Some dental materials, for example, artiicial tooth and orthodontics devices such as arch wire or bracket, are required to exhibit natural sensuousness to make teeth healthy and beautiful. here is therefore concern that TNTZ